The battery choice sets the ceiling for almost everything else in a van's electrical system — how much you can run, how fast you can recharge, how heavy your build is, and how much it costs upfront. Here's the real comparison, not just "lithium is better."
Head-to-Head Comparison
| Lead-Acid (Flooded) | AGM | Lithium (LiFePO4) | |
|---|---|---|---|
| Usable capacity | ~50% of rated | ~50% of rated | 80–100% of rated |
| Cycle life | 300–500 cycles | 400–600 cycles | 2,000–5,000+ cycles |
| Weight (100Ah) | ~60 lbs | ~65 lbs | ~25–30 lbs |
| Charge speed | Slow | Moderate | Fast |
| Cold performance | Poor below freezing | Moderate | Needs low-temp protection or heating |
| Maintenance | Regular (water levels) | None | None |
| Upfront cost (100Ah) | $150–$250 | $200–$350 | $600–$1,000+ |
| Cost per usable Ah over lifespan | Highest | High | Lowest |
Why "Usable Capacity" Changes the Math
A 100Ah lead-acid or AGM battery only safely gives you about 50Ah before you're damaging its lifespan. A 100Ah lithium battery gives you 80-100Ah. That means matching your actual power needs with lead-acid or AGM requires buying roughly double the rated capacity — which erases much of the upfront price advantage once you account for what you can actually use.
Lifespan Changes the Math Again
Lead-acid and AGM batteries typically last 300-600 charge cycles before capacity degrades significantly — roughly 1-2 years of regular van life use. Lithium batteries commonly last 2,000-5,000+ cycles, often outlasting the van conversion itself. Over a 5-year ownership period, most lead-acid/AGM setups get replaced at least once, sometimes twice — a cost that rarely gets included in the "cheaper upfront" comparison.
Weight Matters More Than It Seems
A 200Ah lead-acid bank weighs roughly 120 lbs; the lithium equivalent weighs roughly 50-60 lbs. On a payload-limited van — which is most Sprinter and Transit conversions once cabinetry, water, and passengers are factored in — that 60-70 lb difference is real usable payload you get back for other things.
When Lead-Acid or AGM Still Makes Sense
- Very tight upfront budget with light power needs (occasional weekend use, minimal fridge/lighting draw) where doubling the rated capacity still lands at a lower total cost than lithium.
- Backup or secondary systems where cycle life matters less because the battery is rarely deep-cycled.
- Extreme cold-weather builds without a battery heating solution — standard lithium cells shouldn't be charged below freezing, which AGM handles natively. (Heated lithium options exist but add cost.)
The Case for Lithium in Most Modern Builds
For anyone doing a full-time or frequent-use build, lithium's combination of usable capacity, weight, fast recharge, and long lifespan usually wins on total cost of ownership — even with a higher sticker price — within 2-3 years of regular use. It's why the overwhelming majority of new van conversions since roughly 2022 have shifted to lithium as the default choice.
Frequently Asked Questions
Is lithium worth the extra cost for van life? For most full-time or frequent builds, yes — the usable capacity, weight savings, and lifespan typically make it cheaper per usable amp-hour over a few years of ownership, not just a luxury upgrade.
Can I mix lithium and lead-acid batteries? Not recommended in the same bank — different charge profiles and voltages between chemistries can cause imbalanced charging and reduce the lifespan of both.
Do lithium batteries work in cold weather? Standard LiFePO4 cells shouldn't be charged below freezing (they can still discharge in cold, just not charge safely). Many modern lithium batteries include built-in low-temperature charge cutoffs or optional heating pads to handle this.